The lymphocyte blastogenic responses of chronic schistosomiasis mansoni patients were tested in vitro in medium supplemented with either normal human serum or patients' serum (either autologous or third party). As expected, when patients' lymphocytes were cultured in patient sera, many of them (75–78%) displayed reduced responsiveness to schistosome antigens (derived from either the cercariae, adult worms or eggs of Schistosoma mansoni), but not to Candida albicans extract. For decreased blastogenesis to be manifest, a combination of both suppressive sera and suppressible cells was required; however, some patients had nonsuppressible cells and not all sera were suppressive. In an attempt at classification, four categories of patient responsiveness concerning serosuppression are proposed. The categories depend on the suppressive capabilities of patient sera and the response of patient lymphocytes to suppressive sera. By individually testing the capabilities of each patient's lymphocytes and sera in relationship to each antigenic preparation, we were able to assign the majority of patient responses to a given category. It is hoped that by using these categories, a better understanding of the mechanisms concerning serosuppression will be obtained.
Former staff member of the Rockefeller Foundation; present address: Foreign Mission Board, Southern Baptist Convention, Richmond, Virginia.